But Mr Rogers said the recruits were told to stay in Australia. The senior Republican politician said the note back from IS said: "No, No. What we want you to do, stay in Australia. We want you to randomly kidnap people off the street, behead them, videotape it, send it to us for further propaganda."

On Tuesday, the Department of Homeland Security boosted security at 9500 federal buildings across the US. Mr Rogers linked the alleged IS Australian beheading plot and other intelligence to the security boost.

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"They wanted to have a high-profile event in a Western country," he said.

"They wanted to show that they could reach out and strike a Western country, which is why we believe now you see all of this activity - Canada, the United States, across Europe, Germany, France, Spain, because they're actively working at trying to find an event that happens in a Western country that they can take credit for."